Orthopedic fixation device with magnetic field generator

ABSTRACT

A medical device includes an orthopedic fixation device and an electromagnetic field emitter carried by the fixation device. The device preferably further includes a power source for powering the electromagnetic field emitter, which may be implanted in the human body with the fixation device and the electromagnetic field emitter. The power source may be a battery.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This disclosure relates to orthopedics. More specifically, the inventionrelates to an orthopedic fixation device with an integrated magneticfield generator for placement in a patient to promote healing of afractured bone and surrounding tissue, to reduce infection, reduce bothacute and chronic pain, in arthrodesis procedures, and to reduce edema,as well as for other purposes.

2. Related Art

Electromagnetic fields have been proposed for use for therapeuticpurposes for many years. Heretofore, fields have been generatedexternally and oriented so as to pass through the tissue or bone to betreated. The systems, while effective, have the disadvantage that theyrequire bulky signal generating apparatus and electromagnetic fieldgenerating coils to be worn by the patient. This is a particular problemfor patients who are ambulatory and a lesser but still significantproblem for patients confined to bed.

SUMMARY OF THE INVENTION

The present disclosure remedies the foregoing shortcomings of the priorart by providing an improved medical device for implanting in a patient.

In one aspect of the invention, a device includes an orthopedic fixationdevice and an electromagnetic field emitter carried by the fixationdevice. The orthopedic fixation device may be a rod or plate or similardevice. The device preferably further includes a power source forpowering the electromagnetic field emitter, and a controller that may beseparate from or integrated with the power source for generating avarying signal that is applied to the electromagnetic field emitter, allof which may be implanted in the human body with the fixation device andthe electromagnetic field emitter. The power source may be a battery.

In another aspect of the invention, a device for use in healing a brokenbone includes an internal fixation device having an opening or cavitytherein and an electromagnetic field emitter disposed in the opening orcavity.

In accordance with another aspect of the invention a device for use inhealing a broken bone and for other uses includes an internal fixationdevice carrying an electromagnetic field generator, a signal generator,and a rechargeable power source, together with an external device forrecharging the power source.

An understanding of these and other aspects, features, and benefits ofthe invention may be had with reference to the attached figures andfollowing disclosure, in which preferred embodiments of the inventionare illustrated and described.

BRIEF DESCRIPTION OF THE DRAWING FIGURES

FIG. 1 is a diagram of a fixation device according to a first embodimentof the disclosure.

FIG. 2 is a diagram of an electromagnetic field emitter used in afixation device according to the disclosure.

FIGS. 3A-3C are cross-sectional views of other embodiments of fixationdevices according to the disclosure.

FIG. 4 is a cross-sectional view of another embodiment of a fixationdevice according to the disclosure.

FIG. 5 is a perspective view of a fixation device according to anotherembodiment of the disclosure.

FIG. 6 is a perspective view of a fixation device according to anotherembodiment of the disclosure.

FIG. 7 is a perspective view of a fixation device according to anotherembodiment of the disclosure.

FIG. 8 is a cross-sectional view of a fixation device according toanother embodiment of the disclosure.

FIG. 9 is a cross-sectional view of a fixation device according toanother embodiment of the disclosure.

FIG. 10 is a perspective view of a fixation device according to anotherembodiment of the invention.

FIG. 11 is a perspective view of a field generator and an associatedgenerated field.

FIG. 12 is a perspective view of a series of coils on a substrate,according to another embodiment of the invention.

FIG. 13 is a schematic illustrating a system according to anotherembodiment of the invention.

FIG. 14 is a perspective view of a fixation device according to anotherembodiment of the invention.

FIG. 15 is a plan view of a fixation device according to anotherembodiment of the invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION

The invention relates generally to fixation devices. More specifically,the invention relates to fixation devices that are useful for assistingin fracture and wound healing, treating infection, reducing pain, andfor other therapeutic purposes. Preferred embodiments of the inventionnow will be described with reference to the figures.

FIG. 1 shows a fixation device 10 according to a first embodiment of theinvention. The fixation device generally includes a hollow rod 14 whichis an intramedullary fixation device. Such intramedullary fixationdevices are conventionally known for placement within a bone cavity,especially longer bones such as the femur or the tibia to aid in properrealignment of a bone 2 having a fracture 4. Like conventionalintramedullary rods, the hollow rod 14 illustrated in FIG. 1 may be heldin place using screws 12 such as locking screws. Preferably the rod isfabricated in a size and shape that give it sufficient strength tostabilize the fracture during healing. The rod is fabricated from amaterial that permits a magnetic field to pass there through, eitherbecause the material itself permits the passage of a magnetic field orthe rod is provided with a section through which the magnetic field maypass.

Unlike conventional intramedullary rods, a fixation device 10 accordingto the illustrated embodiment includes an electromagnetic field emitter16 disposed in the cavity 15 of the hollow rod 14. The electromagneticfield emitter 16 may take any conventional shape, and preferablyincludes an electromagnetic coil such as a solenoid coil through which acurrent is passed to create a magnetic field.

A controller 18 which may be fabricated on a printed circuit boardand/or as an integrated circuit is provided in communication with theelectromagnetic coil of the electromagnetic field emitter 16 forgenerating a signal to energize the electromagnetic field emitter 16. Inthe embodiment of FIG. 1, a power source 20, such as a battery, also isprovided within the hollow rod, in communication with theelectromagnetic field emitter 16 and the controller 18. Leads or wires22 also are provided in the hollow rod 14 to interconnect theelectromagnetic field emitter 16, the controller 18, and the powersource 20. Generally speaking, the controller is energized by the powersource to generate the signal that when applied to the electromagneticfield emitter creates a field, preferably a varying field thatintersects the fracture or wound.

In one example of the invention, the controller 18 is programmed with aseries of instructions for controlling the field emitted by theelectromagnetic field emitter 16. More specifically, the controller maybe programmed with a routine such as a series of intensity and/or timedependent instructions. Depending upon the program routine, thecontroller will manipulate the power from the power source to supply acurrent to the electromagnetic field emitter 16, which in turn willcreate an electromagnetic field corresponding to the applied current. Byvarying the current and the time, any number of routines may be used, asrequired by the patient.

The controller may be preprogrammed with a number of routines forapplication of varied electromagnetic fields to the injury site. Forexample, routines may be included that depend upon the location and/orseverity of a fracture or accompanying wounds to nearby tissue and/ormuscle. In still other embodiments, the controller may be programmableeither before implantation into the patient, or after being inserted.One lead may be accessible through the skin to allow tethering to acomputer or the like useable in programming the controller 18.Preferably, the controller will include a wireless receiver configuredto receive programming instructions wirelessly from a computer or thelike equipped with a transmitter. Further, the controller may include awireless transmitter for transmitting data corresponding to the signalgenerated by the controller.

Although in the illustrated embodiment of FIG. 1, the power source andcontroller are disposed within the hollow rod with the electromagneticfield emitter, in other embodiments the power source and/or thecontroller may be disposed in the body, but remote from theelectromagnetic field emitter. In such an arrangement, the wires orleads 22 may extend outside of the hollow rod 14 and connect to theremotely disposed controller 18 and/or power supply 20. In still otherembodiments, the controller and/or the power source may be disposedcompletely outside of the body. For example, the power source may be afield emitter disposed outside the body that emits an electromagneticfield and when placed in proximity to an induction coil disposed in thebody, will charge the coil to power the electromagnetic field generator.Preferably, the field emitter used as the power supply 20 emits a fieldthat is different from the field generated by the electromagnetic fieldemitter, and which will not adversely affect the wound healing sought tobe accomplished by the electromagnetic emitter.

The electromagnetic field emitter generally is a conventional structurethat will emit an electromagnetic field at a frequency of between about5 and about 100 Hz, more preferably between about 5 Hz and about 30 MHz,and at 60-400 Gauss within a treatment volume. As a result of theinvention, the emitter can be placed in close proximity to a fracture ina bone and/or proximate nearby afflicted muscle or other tissue.Although two emitters are illustrated in FIG. 1, more or fewer emittersmay be provided. The emitter(s) preferably are at fixed positions insidethe hollow rod 14. The position of the emitter 16 within the hollow rod14 will be dictated by the position of the rod relative to the positionof the fracture. When the rod 14 is placed in the bone 2, theelectromagnetic field emitter 16 will closely align with the position ofthe fracture to expose the fracture to the electromagnetic field. In apreferred embodiment, the emitter(s) will be affixed to the inside ofthe hollow rod using any known fastener, such as a physical fastenerlike a set screw, or an implant grade adhesive.

As will be appreciated by those of ordinary skill in the art, knownelectromagnetic field emitters produce electromagnetic fields having aknown size and shape. FIG. 2 shows a conventional electromagnetic fieldemitter 160 including a conductive wire, such as copper, 162 wound alongan axis to form a coil. When an electrical current is passed through thecoil, an electromagnetic field is created as depicted by flux lines 168.Although not required, the illustrated coil 162 is wrapped around acylindrical core 164, which is preferably a ferrous core, to intensifythe field.

In use, the coil should be positioned such that the bone fracture and/orany other tissue to be healed is disposed in the electromagnetic field.An advantage of the invention over previously-used, non-implantedelectromagnetic field emitters, is that the field can be generated verynear to the fracture or other wound to be treated so that the high fluxportion of the field can intersect the wound/fracture. This closepositioning allows for a lower power requirement, because the field neednot be as strong as it would need to be if it were generated fartherfrom the fracture and increased biological healing response because thefield is not interfered with by passing through surrounding tissue. Whenthe fixation device is a rod, as in FIG. 1, a series of electromagneticfield emitters like those illustrated in FIG. 2 may be disposed alongthe length of the hollow rod, such that the electromagnetic fieldsoverlap along the length of the rod. In this embodiment any positionalong the rod will be affected by an electromagnetic field. While thecare giver could opt to energize all coils to provide a field along thefull length of the rod, the controller could alternatively be configuredto allow for selective energizing of the coils. In other embodimentsfewer emitters may be provided that are positioned specifically foraffecting the fracture/wound. One or more emitters may be provided thatare moveable within the rod prior to placement of the rod, to allow theemitters to be placed at positions that will best promote healing. Inyet another embodiment of the invention, the emitters may be placed atpredetermined positions within different rods, with the orthopedicsurgeon choosing a rod that will align the emitter with thefracture/wound for healing promotion.

In conventional intramedullary nail placement procedures, a guide wireis passed longitudinally through a fractured bone, a reamer is passedover the guide wire to bore the bone out longitudinally, and the rod isfed over the guide wire into position. Once in position, screws may beinserted transversely through the bone and into the rod, to lock the rodin place. A rod according to the present disclosure may be insertedusing the same procedure. To do so, the rod preferably also has alongitudinal opening, which may require that each of the electromagneticfield emitters and other components occupy less than the fullcross-sectional area of the opening in the rod or have openingsextending axially therethrough.

For example, each electromagnetic field emitter could have a hole formedtherethrough, large enough to allow for passage of the guide wire therethrough. In one embodiment, each of the emitters is a wound coil such asthat shown in FIG. 2. The illustrated coil, also referred to as an aircoil, is illustrated in which a wire is wound continuously along an axispreferably in multiple layers to form a cylindrical coil defining anopen middle. The coil is preferably sized to allow passage of the guidewire through the open middle. In another embodiment it may be desirableto wrap the air coil around a ferrite core. To facilitate passage of thenail over a guide wire, the ferrite core may have a longitudinal openingformed therein.

Other embodiments may also allow use of a guide wire to insert anintramedullary rod by ensuring that the footprint of the electromagneticfield emitter has a smaller area than the area of a cross-section of theopening in the hollow rod. This could be particularly useful when it isdesired to dispose a solid core in the coil. For example, the emittercould be attached to a sidewall of the opening, sized small enough suchthat space is provided next to the emitter large enough to pass a guidewire. A sleeve or conduit could also be provided in the rod to guide theguide wire through a more tortuous path along the length of the rod. Thesleeve or conduit feeds the guide wire in any number of ways, includingthrough the sidewall of the hollow rod. This would be particularlyuseful in applications in which the emitter occupies substantially allof the opening in the hollow rod at axial positions along the rod. In afurther example, the hollow rod may include a completely separate,substantially axial, guide opening 21, which is parallel to the cavity15. An example of this separate opening is illustrated in FIG. 3A, andis formed in a sidewall of the hollow rod. To this end, the hollow rodmay not be cylindrical, but could instead include a profile allowing forboth the cavity 15 and the guide opening 21. Some exemplary profiles areillustrated in FIGS. 3B and 3C.

As will be appreciated, large, concentrated forces are often applied tointramedullary nails and rods during insertion and during healing, andthe components disposed within the rod must be firmly affixed in the rodto avoid damage or dislodgement during insertion and healing.

In another embodiment of the disclosure, the electromagnetic fieldemitter (and power source and controller) may be inserted into the rodafter the rod is inserted into the bone. A stop, such as a constrictionor protuberance, may be provided in the cavity 15 of the hollow rod insuch an embodiment, to attain proper axial positioning of the insertedcomponents. An adhesive may be applied to the inserted components tomaintain their position once inserted. Alternatively, a packing ormechanical stop may be inserted after the inserted components tomaintain positioning of the emitter in the rod. An advantage of theafter-inserted components is that the components do not undergo thepounding and potential destruction accompanying insertion of the rod.

In other embodiments, a guide wire is not used for insertion of thehollow rod, so no provisions for an axial passageway through the rodneed be made. In this example, the opening through the bone is bored orreamed out using known techniques, and the rod is then inserted.

Because the fixation device 10 is generally intended to be left in thepatient permanently, each of the components should be implant grade.Moreover, the hollow rod 14 of the embodiment of FIG. 1 preferably is anon-ferrous material, such as a polymer or titanium so as not to affectthe electromagnetic field emitted by the electromagnetic field emitter16. The components should be chosen such that the electromagnetic fieldemitted by the electromagnetic field emitter 16 will pass freely throughthe fixation device 10 to the fractured bone and/or the damaged tissue.

The invention is not limited to an embodiment in which theelectromagnetic field emitter is disposed within a hollow rod comprisinga fixation device. In an alternative to the foregoing embodiments, theelectromagnetic field emitter could be disposed on a side of the hollowrod 14 or at an end thereof. In such an embodiment, it may not benecessary that the hollow rod 14 be hollow at all. A solid rod could beused instead, because no components are intended to be disposed withinthe rod.

In another embodiment, the coil comprising the emitter could be wrappedaround the rod. This embodiment is shown in FIG. 4. In that figure,emitters 16 are formed at spaced positions along the rod 14 by wrappingwire around the rod 14. Although this embodiment shows a plurality ofdiscrete coils along the length of the rod, the wire may be wrappedcontinuously along the entire length of the rod, to create a largerfield. In these embodiments, all or a portion of the rod may be ferrous,to intensify the field at each coil. Alternatively, the rod could stillbe hollow, but with ferrous material disposed in the hollow rod. Thecontrol and power supply could also be disposed in a hollow rod.

The embodiment illustrated in FIG. 4 also includes a protective layer 26formed over the coils. This protective layer 26 preferably is chosen toshield the coils from damage when the rod is inserted by an orthopedicsurgeon. For example, the protective layer may be a polymeric or foilwrap disposed over the coil, and which will not affect the field emittedby the coils. FIG. 4 also shows a leading protrusion 24 disposed axiallyadjacent to each coil. The protrusion extends radially from the rodfurther than the coil and is disposed such that when the rod is insertedalong the direction of arrow in FIG. 4, the protrusion first enters thebone. In this manner, the protrusion forges a path through the bone tominimize contact of the bone with the coil, thereby reducing thepotential for damage to the coil.

In alternatives to FIG. 4, one or both of the protective layer 26 andthe protrusion 24 may not be provided. The protrusion may be an annularring disposed about the circumference of the rod, or it may be a seriesof protrusions disposed about the circumference. Moreover, asillustrated in FIG. 4, the protrusion preferably is angled, to promoteease of insertion of the rod into the bone.

The invention also is not limited to an intramedullary rod or nail. FIG.5 shows an embodiment of the invention in which a fixation device 110 isincorporated in a screw 112 having a threaded shaft 112 a and a head 112b. There, an electromagnetic field emitter 116 comprising a plurality ofwindings as a coil like that in FIG. 2 is disposed on a shaft of thescrew 112, proximate the head 112 b. The electromagnetic field emitterthus will not inhibit access to the head of the screw, for example, forinsertion, but the emitter can be placed wherever a screw can beinserted. The screw may be a locking screw such as the type used inconnection with an intramedullary rod or a plate, or it may be any othertype of screw, including but not limited to a pedicle screw for use inspinal procedures.

As also illustrated in FIG. 5, the screw 112 further includes an annularstop 128 arranged between the threads and the coil. When an orthopedicsurgeon inserts the screw, rotation of the screw will be stopped whenthe stop 128 contacts the bone or plate into which the screw is beinginserted. In this way, the surgeon will not overtighten the screw in amanner that will cause the coil to contact the bone or plate, resultingin potential damage to the coil. Although not illustrated, leads willextend from the coil to the controller and/or power source, as inprevious embodiments. Such components may be provided on the screw, orin a separate implant.

Yet another embodiment of the invention is illustrated in FIG. 6. FIG. 6is similar to the previous embodiments in that it shows a fixationdevice 210 including an implant 214 and an electromagnetic field emitter216. Unlike the other embodiments, the implant is a plate 214, such as asurgical or orthopedic plate, and the emitter 216 is a coil carried onthe plate. The plate may be any known plate or plate-like structure, forexample, such as used to maintain position of a fractured bone forhealing that bone or for fusion of bones, as in spinal surgery. In thepreferred embodiment, the emitter 216 is carried on a side of the plate214 that does not contact the bone. The emitter 216 may be fixed to theplate in any number of ways, including fasteners and adhesives. FIG. 6also shows a controller 218 and power source 220 carried on the plate,and electrical leads 222 interconnecting the foregoing components. It ispreferred that the plate be made from a material that will not distortthe field generated by the emitter, but the emitter and plate may bedesigned to cooperate in creating a field that will effectivelyintersect with a fracture/wound.

The emitter may be mounted on any position of the plate, to ensuremaximum exposure of the fracture to the generated field. In someembodiments, the orthopedic surgeon will affix the emitter duringsurgery, using known fastening means, such as adhesives or mechanicalfasteners. In other embodiments, an emitter or emitters may be fixed atpredetermined position(s) on the plate. The surgeon will then choose theappropriate plate, and place the plate to ensure that the emitted fieldis properly aligned with the injury. FIG. 6 also illustrates indicia ora registration mark 224 (a dotted line in the figure) that will allow auser to readily properly align the plate for healing using the emitter.In the illustrated embodiment, the surgeon aligns the dotted line 224with the break to ensure that the emitter will be properly aligned.

In yet another embodiment, illustrated in FIG. 7, an emitter 316includes a coil 328 such as those described above and a protrusion 330depending from the coil. The protrusion 330 is sized to allow forregistration of the emitter 316 with any standard hole 315 formed in anorthopedic plate 314. As will be appreciated, orthopedic platesgenerally have a plurality of holes 315, to allow a surgeon maximumflexibility for affixation of the plate to the bone. Any hole or holesaligning with the fracture are generally not used, because a screw israrely used at the break. However, it is beneficial to align the emitterwith the break, for reasons discussed above. The protrusion 330 of thisembodiment allows for registration of the emitter with the plate at thebreak. The protrusion may form a press or interference fit with theplate, facilitating connection of the emitter with the plate.Alternatively, the emitter with protrusion may be fixed to the plateusing any known fastening method, such as adhesives. A controller and/ora power source may be included with the emitter or may be positionedanywhere on or spaced from the plate.

Although the foregoing embodiments describe securing the emitter to thetop of the plate, the emitter may be disposed anywhere on the plate,including on an edge of the plate or the bottom of the plate, proximatethe bone to which the plate is affixed. In another embodiment,illustrated in FIG. 8, an electromagnetic field emitter 316 is disposedin a recess 313 formed in a plate 314. The plate 314 further includesholes 315 for affixation of the plate. A controller 318 and a powersource 320 are also illustrated in the recess 313. The recess 313 allowsfor a lower-profile arrangement than can be achieved by placing theemitter on top of the plate. The recessed portion of the plate should beconfigured to provide sufficient rigidity to stabilize the fracture andminimize the formation of stress risers.

FIG. 9 is a modification of the embodiment of FIG. 8 in which an emitter416, a controller 418 and a power supply 420, with interconnections 422,are completely encapsulated within an orthopedic plate 414. In thisembodiment, a cavity 413 is provided in the plate 414 and the componentsare disposed in the cavity. To facilitate formation of the plate 414,the plate may be made of multiple pieces that are assembled afteraffixation of the emitter 416 and other components to one of the pieces.For example, the plate may have first and second opposing pieces, e.g.,a top and a bottom having facing horizontal surfaces that when assembleddefine a cavity sized to receive the emitter and other components, asappropriate. Alternatively, the plate may be formed with a recess, as inFIG. 8, the components placed in the recess, and then a cover applied tosubstantially encapsulate the components in the plate. In suchembodiments, the surgeon will preferably receive a unitary piece inwhich is embedded the components, such as the emitter, controller andpower supply.

As with previous embodiments, the plate used in FIGS. 6-9 preferably isnon-ferrous, such that the emitted electromagnetic field will readilypass through the plate to the treatment area.

Although the embodiments illustrated until now utilize air or axialcoils such as those illustrated in FIG. 2, other types of coils may beused. FIG. 10 shows an embodiment in which the electromagnetic fieldemitter is a flat or pancake coil 516 disposed on a plate 514, such asan orthopedic plate. A pancake coil generally emits a field having fluxlines 568 such as those illustrated in FIG. 11. FIG. 11 also illustratestreatment regions 570, which are areas disposed in the magnetic field.In practice, the afflicted bone or tissue to be healed should bedisposed in these treatment regions 570 for maximum efficacy of theemitter 516.

In the embodiment of FIG. 10, a plurality of pancake coils is providedin a two-dimensional array, i.e., a 1×4 matrix, on a plate 514. Usingappropriate controls, the coils may be selectively energized at desiredfrequencies and for preferred durations. For example, when a plate suchas that illustrated in FIG. 10 is used, the coil or coils closest to thefracture site will be energized according to a first treatmentmethodology. Other coils may be energized differently or not at all. Inother embodiments, more or fewer pancake coils may be provided.Moreover, the pancake coils may be encapsulated in the plate, instead ofdisposed on the plate, as in the embodiment of FIG. 9.

Another embodiment of the invention is illustrated in FIG. 12. There, aplurality of pancake coils 616 is provided on a flexible substrate 614.The flexible substrate allows for form-fitting of the array of coils toa surface. The array of coils may be formed from wrapped wire, but morelikely will be formed by depositing a metal, such as copper, onto thesubstrate as a coil using known deposition, including known maskingand/or etching, techniques. The deposited coil may be a single-layercoil or may include turns in multiple layers. That is, deposited pancakecoils may be stacked one on top of the next. In such a configuration, anintermediate layer, such as an insulating layer, may also be providedbetween stacked coils. Such an arrangement will provide an increasednumber of turns for the coil, but still provide a relatively lowprofile.

The substrate according to the embodiment of FIG. 12 preferably is madeof a polymer-blend. The flexible substrate may be affixed to a plate,such as a conventional plate, or in some embodiments could be affixeddirectly to a patient's bone. An adhesive may be disposed between theback of the substrate and the site to be treated to adhere thesubstrate. The adhesive may be pre-applied and exposed by removing abacking or other protective coating, or it may be applied at the time ofaffixation of the substrate. The substrate could otherwise be affixedusing any known methodology.

The flexible substrate with electromagnetic emitters has the benefit ofallowing for adaptation of existing orthopedic devices, i.e., byaffixing the substrate to such devices. Any number of fixation devicescould be modified to include a substrate including coils. For example,one or more coils on a flexible substrate may be disposed on anintramedullary rod, either wrapping around the rod, or along the lengthof the rod. In other uses, the substrate could be applied directly to abone or other anatomical structure in the body.

In any of the foregoing embodiments, it is preferable to arrange theelectromagnetic field emitter such that in use the emitted field acts onthe desired treatment area. Although the embodiments of FIGS. 6-11generally illustrate coils with axes perpendicular to a top surface of aplate, the coils could readily be provided “on their side” such thattheir axis is parallel to the top surface of the plate without departingfrom the spirit and scope of the invention.

In several embodiments described above, a device according to theinvention generally includes an implantable device, such as aconventional device like a rod or plate, adapted to carry a fieldemitter and a signal generator. Other combinations also arecontemplated. The field emitter and signal generator also may be carriedby an implant such as a prosthesis. For example, during a hipreplacement, a portion of the femur is removed and replaced with animplant including a new ball attached to a stem and a cooperating pieceincluding a socket. The field emitter and signal generator may becarried by the ball or by the shaft of the implant. In one embodiment,the ball and/or shaft may be hollow, with the field emitter and signalgenerator being disposed in the hollow ball or shaft. Those of ordinaryskill in the art will appreciate that alternative, similar embodimentscan also be achieved using the teachings of this disclosure.

The power source provided in the invention may be any known or developedpower source sufficient to power the coil. Batteries have beenconventionally implanted into the human body, e.g., in pace makers, andsuch powering technology may be applicable with embodiments of theinvention.

The control circuitry preferably is provided to allow for user selectionof strength and duration of currents applied to the electromagneticemitters. The controller may be programmable, i.e., via remote controlthrough an input device external to the patient, to allow for customtreatment of each patient. In other embodiments, the controller could bepre-programmed with a treatment methodology and merely turned on to runthrough that pre-determined treatment regimen. The control circuitry mayfurther include wake-up circuitry or the like, to allow for delayedoperation. For example, an orthopedist may determine that they wouldprefer not to use the electromagnetic field therapy until some amount oftime after surgery. Thus, the emitter should not be energized until thattime, if at all.

As noted above, a number of arrangements of electromagnetic fieldemitters, signal generating electronics, i.e., to instruct energizing ofthe coil, and power sources, which provide power for energizing thecoil, will be appreciated from this disclosure. In a relatively simpleembodiment, a battery, as the power source, the signal generatingelectronics, and a wire coil are implanted directly in a patient. Thesignal generating electronics will include pre-programmed operationalsequences as treatment routines that will energize the coil as desired.

In addition to a battery, signal generating electronics and a magneticcoil, the implanted device may further include a receiver and atransmitter, allowing the device to communicate with an external device.Such an arrangement would allow for downloading to the implanted devicesignal patterns and schedules, e.g., for specific treatments, as well asupdates, and for receiving information from the device, for example,about the treatment, such as accumulated dosimetry and/or othertreatment characteristics.

In yet another embodiment of the invention, to assist in providinguseful information about the device implanted into the body, the devicemay further include sensory coils. Such coils are spaced from theelectromagnetic field emitters to receive the generated magnetic fieldat a known distance from the generating coil. The receiver coil isplaced at a position, such as a position spaced along the implanteddevice away from the emitter or an opposite side of a fracture to betreated, to measure the magnitude and duration of the generated magneticfield. Using the aforementioned transmitter, the results measured by thesensor coil are then forwarded to the remote device, for interpretationby a doctor or technician.

Although many of the foregoing embodiments entail implanting a batteryas a power source, in some applications a battery may not be the bestpower source. For example, it may be impractical to use a conventionalbattery, for example, because the battery may not last long enough. Whenchronic pain is being treated using a device according to the invention,it is preferable that the device function as long as the patientrequires. Thus, the device may further include an induction coil as arechargeable power source. More specifically, the induction coil isimplanted in the patient and an induction device, such as an inductionwand, is used external to the patient to charge the device. The wand maytake any known form including being provided in a wearable device thatcould charge the device, for example, when the user is sleeping.

FIG. 13 illustrates a schematic of a system according to the invention.There, a battery 42 is the power source, and an induction loop 44 isprovided to charge the battery 42. A receiver 46 and transmitter 48 arealso illustrated, as is an example of the signal generator 50. Thesignal generator 50 is illustrated as including a signal shape memory52, which stores one or more signal shapes used to drive the coil 60; asignal playback generator 54; signal level controls 56; and finaltreatment amplifier 58. These components all are connected to thetreatment coil 60. The schematic also shows a sensor coil 62, such asthat described above, and controls 64 for receiving information from thesensor coil 62. This schematic is provided merely as an example; othersystems and configurations will be apparent to those of ordinary skillin the art upon being educated by this disclosure.

The invention has been generally described herein as utilizing a coil asan electromagnetic field emitter. Other embodiments may includedifferent field generators. For example, an alternative embodiment mayinclude a permanent magnet, having a known field strength and shape. Themagnet could then be vibrated, rotated or otherwise moved to modulatethe field, to apply the desired bioeffect. FIG. 14 shows an example ofthis. There, a permanent magnet 716 generates a magnetic field having aknown strength and shape. The magnet 716 is disposed on a shaft 790,rotatable by a rotary actuator 792, such as a piezoelectric actuator. Byrotating the magnet, the magnet's field is modulated, which modulationmay be optimized for treatment of a broken bone or wound. Thus, theactuator/permanent magnet combination forms a controllable magneticfield emitter. Although not illustrated, the actuator/permanent magnetfield emitter will be carried on a fixation device or other implantablecarrier, such as an orthopedic plate, intramedullary rod, replacementimplant, or the like.

Although a rotary actuator is illustrated in FIG. 14, this is merely forillustrative and exemplary purposes. In an alternative embodiment, shownin FIG. 15, the magnet 816 is provided on a linear actuator 892, such asa piezoelectric actuator, disposed to move along the direction indicatedby the arrow in FIG. 15. By actuating the actuator 892, a fracture 804in a bone 802 is selectively disposed in and spaced from the magnet'sfield, indicated by flux lines 868. A signal generator for driving theactuator also is shown in FIG. 15. The magnet 816 and the actuator 892are illustrated in this embodiment as being disposed in a hollow rod814. In other embodiments those components could be carried on any otherimplant, including but not limited to those described above

While the invention has been described in connection with severalpresently preferred embodiments thereof, those skilled in the art willappreciate that many modifications and changes may be made thereinwithout departing from the true spirit and scope of the invention whichaccordingly is intended to be defined solely by the appended claims.

1. An orthopedic device comprising: an internal orthopedic fixationdevice; and a magnetic field emitter carried by the fixation device. 2.The orthopedic device of claim 1, further comprising a power source formodulating a magnetic field emitted by the magnetic field emitter. 3.The orthopedic device of claim 2, wherein the power source is a batteryimplanted in the human body with the fixation device and the magneticfield emitter.
 4. The orthopedic device of claim 2, wherein the powersource is a field generator generating a field that will charge theelectromagnetic field emitter.
 5. The orthopedic device of claim 4,wherein the field generated by the field generator is different from thefield generated by the magnetic field emitter.
 6. The orthopedic deviceof claim 1, wherein the fixation device comprises a hollow rod and themagnetic field emitter is disposed in the hollow rod.
 7. The orthopedicdevice of claim 1, wherein the fixation device is a plate.
 8. Theorthopedic device of claim 7, wherein the plate comprises a cutoutadapted to receive the magnetic field emitter therein.
 9. The orthopedicdevice of claim 7, wherein the magnetic field emitter is affixed to theplate.
 10. The orthopedic device of claim 1, wherein the fixation deviceis non-ferrous.
 11. The orthopedic device of claim 1, wherein thefixation device is a screw and the magnetic field generator is anelectromagnetic field emitter disposed proximate a head of the screw.12. The orthopedic device of claim 1, wherein the magnetic field emittercomprises an electromagnetic coil.
 13. The orthopedic device of claim12, further comprising a controller for controlling the electromagneticfield emitted by the electromagnetic coil.
 14. A method of treating aninjury comprising: placing an orthopedic fixation device in a patient;placing an electromagnetic field emitter carried by the device into thepatient; and activating the electromagnetic field emitter to emit anelectromagnetic field proximate the injury.
 15. The method of claim 14,wherein the step of activating the electromagnetic field emittercomprises controlling the emitter to deliver a prescribedelectromagnetic field regimen.
 16. The method of claim 15, wherein theregimen includes one or more of predetermined frequencies and durations.17. The method of claim 14, further comprising securing the fixationdevice to a bone of the patient.
 18. The method of claim 14, furthercomprising powering the electromagnetic field emitter with a powersupply.
 19. The method of claim 18, wherein the power supply is placedin the patient along with the fixation device.
 20. A device forstabilizing a fracture and promoting healing, comprising: anintramedullary orthopedic fixation device having an opening therein; anelectromagnetic field emitter disposed in the opening of the orthopedicfixation device; a controller disposed in the opening of the orthopedicfixation device and communicating with the electromagnetic field emitterto control the field emitted by the electromagnetic field emitter; and apower source providing power to the controller and the electromagneticfield emitter.